Alzheimer's disease (AD) is the most common form of dementia occurring in mid- to late-life. The prevalence of AD and associated health-care costs are expected to increase in the future, due to shifts in life-expectancy and demographics. Gene therapy may provide a treatment for AD. It has been demonstrated that ex vivo nerve growth factor (NGF) gene transfer can prevent neuronal death and reverse decline of cholinergic neurons associated with aging. These findings have led to the first clinical trial of gene therapy to treat an age-related neurodegenerative disorder. However, ex vivo gene delivery may not be practical for wide-scale commercial application. In vivo gene therapy, where vectors are directly injected into the brain, is a more feasible approach. This project will determine whether regulatable in vivo gene transfer can deliver therapeutic molecules to the brain in a safe and effective manner. In addition, the efficacy of regulatable in vivo NGF delivery to reduce neuronal degeneration and ameliorate cognitive decline will be tested in rodent models relevant to AD. Results from this project will support an IND application for regulatable in vivo gene therapy for AD. Hopefully, successful results will lead to eventual commercialization of this process as a therapeutic for AD.